In all cases I've encountered, it's a simple value that needs to be changed. Plus, they don't have to resize anything. The maps don't exist in the same space, so putting a map "inside" another map can't happen.

"the Living World in the second quarter Episode IV update, players can continue to get the dry highlands (new map of the scene) achievements and awards, this chapter also will bring more bonus content, so stay tuned!"

This isn't really mentioned anywhere, but when you finish the current backpiece it also gives you a new seed: Cultivated Seed.

It's description reads: The first seed cultivated and produced by your own hand. To cultivate this specimen to be even better than the last, perhaps another type of magically infused clay pot is necessary.